iPhone Development 101

The launch image (or default image) is displayed while your app
launches. (If no default image is provided, then a black screen is
displayed.)
To include a launch image in your app, add images of the appropriate size for the device, and name them as follows:

iPhone 4S3.5" display

iPhone 54" display

Non-retina

320 x 480 pixelsDefault.png

N/A

Retina

640 x 960 pixelsDefault@2x.png

640 x 1136 pixelsDefault-568h@2x.png

Note that the Default-568h@2x.png image is required for an app to display in full-screen mode on the iPhone 5.
Launch images for the iPhone are only accepted in portrait mode. If
you want to provide a landscape launch image, create the image and
rotate it 90 degrees in an image editor, then save as named above.

iPad - Portrait

iPad - Landscape

Non-retina

768 x 1004 pixelsDefault-Portrait.png

1024 x 748 pixelsDefault-Landscape.png

Retina

1536 x 2008 pixelsDefault-Portrait@2x.png

2048 x 1496 pixelsDefault-Landscape@2x.png

iPad launch images do not include the status bar area.
You can provide different launch images for each orientation (Portrait,
PortraitUpsideDown, LandscapeLeft, and LandscapeRight); consult the
Apple documentation for details.